Overcurrent Faults in VFDs: Diagnoses and Treatments
Are you working with a Variable-Frequency Drive (VFD)? Many conditions can impact the relationship between your VFD and motor, leading to an overcurrent fault.
Common Scenarios that lead to Overcurrent Faults in VFDs
A motor may be subject to a front impact or can be mechanically seized, which leads to a sudden increase in the current draw.
The VFD may have an output short. For example, there might be a motor cable issue or a short inside the motor itself.
A drive could be running abnormally due to internal component degradation.
The VFD speed acceleration or deceleration time is set too low. If that happens, the drive may need to put out a higher current than it can provide.
Treatments for Overcurrent Faults
Resolving a VFD overcurrent at startup:
Inspect the machine to see if it’s stuck or bound in some way, preventing the motor from turning.
Ensure the motor is not shorted.
Use a megger to check if the ground is not shorted to any legs of the motor.
Verify that the power module of the VFD is not damaged or shorted.
Match the starting torque of the motor to drive parameters.
Treating an overcurrent that happens while running:
If the acceleration time is set too low, increase drive acceleration time.
If deceleration time is set too low, increase the deceleration time.
Need an Expert’s Touch?
At American Industrial, we’ll be glad to repair your VFD and any other motor controls you may have. We’ll provide a free evaluation of the problem and we can repair and return your part faster than the OEM. Plus, your motor control is covered by our 24-month service warranty.
Click here to learn more about our motor control repair services.
Have a part you need repaired? Give us a call at (800) 824-2234 or fill out our contact form.
Other blog posts you may enjoy:
The Benefits of Partnering with American Industrial
Robotic Systems Repair: A Cornerstone Service
How Our Relationship with Marposs Benefits You